Professor Brown has shown that "almost every incident in Chrétien's Iwain was suggested by an ancient Celtic tale, dealing with the familiar theme of a journey to win a fairy mistress in the Otherworld.  The fay whom Iwain marries is called Laudine; and, like one of the fairies who live in sacred waters, she has her favourite fountain which the knight guards, as though he were the Black Knight in the old Welsh tale of The Lady of the Fountain.  Both Gaston Paris and Alfred Nutt have also recognized the tale of Iwain as a fairy romance... (The Fairy-Faith in Celtic Countries, Evans-Wentz, 1911)